Significant improvements in animal performance, efficiency and carcass and meat quality have been made over the years through the application of standard animal breeding and selection techniques. However, such classical animal breeding techniques require several years of genetic evaluation of performance records on individual animals and their relatives and are therefore very expensive. Other efforts have been made to improve productivity and quality through the application of such management practices as the use of feed additives, animal hormonal implants and chemotherapeutics. However, there is resistance to the introduction and use of such methodologies. Such methodologies are also non-inheritable and need to be applied differently in every production system.
There is a need for methods that allow relatively easy and more efficient selection and breeding of farm animals with an advantage for an inheritable trait of circulating leptin levels, feed intake, growth rate, body weight, carcass merit and carcass composition. The economic significance of the use of genetic markers that are associated with specific economically important traits (especially traits with low heritability) in livestock through marker-assisted selection cannot therefore be over-emphasized.
The physiological regulation of intake, growth and energy partitioning in animals is under the control of multiple genes, which may be important candidates for unraveling the genetic variation in economically relevant traits (ERT) in beef production. Polymorphisms in these candidate genes that show association with specific ERT are useful quantitative trait nucleotides for marker-assisted selection.
The fibroblast growth factor (FGF) family consists of at least eighteen distinct secreted proteins (Basilico et al., Adv. Cancer Res. 59:115 165, 1992 and Fernig et al., Prog. Growth Factor Res. 5(4):353 377, 1994) that interact with the FGF tyrosine kinase recptors, and which generally act as mitogens for a broad spectrum of cell types. For example, basic FGF (also known as FGF-2) is mitogenic in vitro for endothelial cells, vascular smooth muscle cells, fibroblasts, and generally for cells of mesoderm or neuroectoderm origin, including cardiac and skeletal myocytes (Gospodarowicz et al., J. Cell. Biol. 70:395 405, 1976; Gospodarowicz et al., J. Cell. Biol. 89:568 578, 1981 and Kardami, J. Mol. Cell. Biochem. 92:124 134, 1990). In vivo, bFGF has been shown to play a role in avian cardiac development (Sugi et al., Dev. Biol. 168:567 574, 1995 and Mima et al., Proc. Nat'l. Acad. Sci. 92:467 471, 1995), and to induce coronary collateral development in dogs (Lazarous et al., Circulation 94:1074 1082, 1996). In addition, non-mitogenic activities have been demonstrated for various members of the FGF family. Non-proliferative activities associated with acidic and/or basic FGF include: increased endothelial release of tissue plasminogen activator, stimulation of extracellular matrix synthesis, chemotaxis for endothelial cells, induced expression of fetal contractile genes in cardiomyocytes (Parker et al., J. Clin. Invest. 85:507 514, 1990), and enhanced pituitary hormonal responsiveness (Baird et al., J. Cellular Physiol. 5:101 106, 1987)
FG-8 is a member of the FGF family that was originally isolated from mammary carcinoma cells as an androgen-inducible mitogen. It has been mapped to human chromosome 10q25-q26 (White et al., Genomics 30:109 11, 1995). FGF-8 is involved in growth and patterning of limbs (Vogel et al., Development 122:1737 1750, 1996; Yoshiura et al., Am. J. Med. Genet. 72: 354-362 and Tanaka et al., Current Biology 5(6):594 597, 1995) Expression of FGF8 during embryogenesis in cardiac, urogenital and neural tissue indicates that it may play a role in development of these tissues (Crossley et al., Development 121:439 451, 1995) There is some evidence that acrocephalosyndactylia, a congenital condition marked by peaked head and webbed fingers and toes, is associated with FGF8 point mutations (White et al., Genomics 30:109 11, 1995)
The complete function of FGF8 is still unknown; however, recent studies have linked FGF8 to a number of Quantitative Trait Loci affecting obesity in mice which indicates its potential for regulating adiposity in other species. In addition, Stylianou et al. (Mamm. Gen. 17, 22-36, 2006) suggests that FGF8 might act as a master regulator or interacting element controlling multiple genes that contribute to adiposity.
FGF8 has five exons, in contrast to the other known FGFs, which have only three exons. The first three exons of FGF-8 correspond to the first exon of the other FGFs (MacArthur et al., Development 121:3603 3613, 1995.) The human gene for FGF-8 codes for four isoforms which differ in their N-terminal regions: FGF isoforms a, b, e, and f; in contrast to the murine gene which gives rise to eight FGF-8 isoforms (Crossley et al., Development 121:439 451, 1995) Human FGF-8a and FGF-8b have 100% homology to the murine proteins, and FGF-8e and FGF-8f proteins are 98% homologous between human and mouse (Gemel et al., Genomics 35:253 257, 1996.)
Several studies have focused on the structure and function of human FGF8 (Gemel et al., Genomics 35: 253-257, 1996; Yoshiura et al. Am. J. Med. Genet. 72: 354-362, 1997) and mouse FGF8 (Crossley and Martin, Development, February 121(2); 439-451, 1995; Tanaka et al. PNAS USA 89; 8928-8932, 1992), but not much is known about it in other species. Human FGF8 maps to chromosome 10 and consists of 6 exons, with exons 2 and 3 encoding the C terminus showing 100% alignment with the corresponding mouse exons (Gemel et al., Genomics 35: 253-257, 1996). FGF8 androgen induced property was first discovered in earlier experiments by Tanaka et al. (PNAS USA 89; 8928-8932, 1992). This study reported that a mouse mammary carcinoma cell line was stimulated to secrete a number of FGFs when induced by androgens. These FGFs in turn demonstrated growth like properties on this carcinoma cell line. Isolation and characterization of the activity determined that FGF8 was contributing to some of the growth effects.
Polymorphisms in a candidate gene, such as FGF8, that show association with specific ERT may be useful quantitative trait nucleotides for marker-assisted selection. It remains advantageous to provide further SNPs, such as FGF8 SNPs, that may more accurately predict the meat quality phenotype of an animal and also a business method that provides for increased production efficiencies in livestock cattle, as well as providing access to various records of the animals and allows comparisons with expected or desired goals with regard to the quality and quantity of animals produced.
Citation or identification of any document in this application is not an admission that such document is available as prior art to the present invention.